In U.S. Pat. No. 3,942,338 a roll for a roll conveyor is journaled for rotation relative thereto on a hexagonal supporting and driving shaft extending through the roll. Radially compressible tubular elements are disposed within the roll between the shaft and an encircling internal wall of the roll. A commercially produced roll conveyor constructed according to the disclosure of said patent has a series of such rolls mounted between longitudinally extending side frame members with sprockets or the like mounted on a projecting end of the drive shaft for each roll in rigid connection therewith to drive the shaft. Upon a predetermined resistance to rotation of the rolls, the radially compressible tubular elements are squeezed together and can rotate around each shaft within the roll thereby providing a torque-overload clutch between the shaft and the roll.
A serious problem with the commercial application of the concept disclosed in the aforesaid patent is that should it be necessary or desirable to replace even one of the radially compressible tubular elements the conveyor must be substantially completely disassembled. For example, should it be found that the torque-transmitted between one of the shafts and its companion roll was insufficient to drive the roll, an entire side frame member would have to be removed in order to permit replacement of the tubular element, or should it be found that a tubular element had become defective, similar disassembly of the entire conveyor would be required.
In a production environment where accumulating type roll conveyors are normally used, the time required to dismantle the conveyor of the type contemplated in the aforesaid patent imposes a serious limitation on the suitability of such conveyor for production applications. To disassemble even a short length of such a conveyor would require a number of hours of time during which the conveyor is obviously out of operation. Furthermore, as the torque transmitting force provided by the radially compressible tubular elements is essentially arrived at by a fit-and-try method, the tubular elements may be replaced and the conveyor assembled only to find that they still are not of the proper torque-transmitting capability requiring further disassembly of the conveyor in order to try out different tubular elements.
Therefore, I have discovered that in order to provide a commercially satisfactory conveyor of the accumulating roll type having a torque-overload clutching mechanism it is desirable to be able to remove the torque-transmitting elements without disturbing the conveyor rolls.